Multi-resolution analysis on the spatial refractive index inhomogeneities in the connective tissue regions of human
cervix reveals clear signature of multifractality. We have thus developed an inverse analysis strategy for extraction and
quantification of the multifractality of spatial refractive index fluctuations from the recorded light scattering signal. The method is based on Fourier domain pre-processing of light scattering data using Born approximation, and its subsequent analysis through Multifractal Detrended Fluctuation Analysis model. The method has been validated on several mono- and multi-fractal scattering objects whose self-similar properties are user controlled and known a-priori. Following successful validation, this approach has initially been explored for differentiating between different grades of precancerous human cervical tissues.
KEYWORDS: Optogenetics, Thalamus, Brain, Chemical analysis, Modulation, Neurons, In vivo imaging, Optical fibers, Neurological disorders, Animal model studies
Here, we introduce a computational procedure to examine whether optogenetically activated neuronal firing recordings
could be characterized as multifractal series. Optogenetics is emerging as a valuable experimental tool and a promising
approach for studying a variety of neurological disorders in animal models. The spiking patterns from cortical region of
the brain of optogenetically-stimulated transgenic mice were analyzed using a sophisticated fluctuation analysis method
known as multifractal detrended fluctuation analysis (MFDFA). We observed that the optogenetically-stimulated neural
firings are consistent with a multifractal process. Further, we used MFDFA to monitor the effect of chemically induced
pain (formalin injection) and optogenetic treatment used to relieve the pain. In this case, dramatic changes in parameters
characterizing a multifractal series were observed. Both the generalized Hurst exponent and width of singularity
spectrum effectively differentiates the neural activities during control and pain induction phases. The quantitative nature
of the analysis equips us with better measures to quantify pain. Further, it provided a measure for effectiveness of the
optogenetic stimulation in inhibiting pain. MFDFA-analysis of spiking data from other deep regions of the brain also
turned out to be multifractal in nature, with subtle differences in the parameters during pain-induction by formalin
injection and inhibition by optogenetic stimulation. Characterization of neuronal firing patterns using MFDFA will lead
to better understanding of neuronal response to optogenetic activation and overall circuitry involved in the process.
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